The objectives of this research (long-term) are: (1) to isolate the human plasma follicle-stimulating and luteinizing hormones (FSH and LH) in the presumed multiple discrete components in which these circulate in the blood, (2) to characterize such highly-purified components chemically, biologically and immunologically with a view to identifying the components which represent the biologically active form of FSH and of LH, appropriate for use as plasma standard preparations, and (3) to measure the active circulating form of the pituitary gonadotropins in terms of these standards in: (a) normal individuals of various ages, (b) individuals treated with Clomid, FSH-LH-RH and sex steroids, and (c) patients with reproductive disorders.